Organopolysiloxane resins having Si-bonded vinyl groups are described in U.S. Pat. No. 4,242,486 to Wacker-Chemie GmbH. These organopolysiloxane resins are prepared by reacting (A) an organopolysiloxane having at least 0.1 percent by weight of Si-bonded hydroxyl groups and at least 50 mol percent of monoorganosiloxane units with (B) an organosiloxane containing from 2 to 10 silicon atoms per molecule and having on the average at least two such hydrocarbon radicals for each silicon atom in which at least one of the siloxanes (A) and/or (B) has an average of at least one SiC-bonded vinyl group per molecule, at a temperature of 90.degree. C. .+-. 5.degree. C. in the presence of (C) an acid activated clay, in which the water released during the condensation of Si-bonded hydroxyl groups is retained in the mixture.
In contrast to the process described above, the process of this invention can be conducted at temperatures outside the limited temperature range of 90.degree. C. .+-. 5.degree. C. Also, the process of this invention can be conducted in the presence of a basic catalyst, whereas the process described above was conducted in the presence of an acid activated bleaching clay. Furthermore, the process of this invention utilizes not only organofunctional organosiloxanes, but also organofunctional organosilanes.
Therefore, it is an object of the present invention to provide a process for preparing organopolysiloxanes having SiC-bonded organofunctional groups. Another object of this invention is to provide a process for preparing organopolysiloxanes having SiC-bonded organofunctional groups from organofunctional organosilanes. Still another object of this invention is to provide a process for preparing organopolysiloxanes having SiC-bonded organofunctional groups in the presence of basic catalysts. A further object of the present invention is to provide a process for preparing organopolysiloxanes having SiC-bonded organofunctional groups over a broad temperature range. A still further object of this invention is to provide a process for preparing organopolysiloxanes having SiC-bonded organofunctional groups which may be utilized in manufacturing contact lenses.